Ubiquinol, the reduced form of coenzyme Q10, has a hydroquinone structure as an active center and shows an efficient antioxidative activity. The radical-scavenging reactions of phenolic antioxidants, such as hydroquinone and vitamin E, occur via electron transfer or hydrogen-atom transfer as a rate-determining step. However, little is known about the detailed mechanisms of radical-scavenging reactions of hydroquinones. On the other hand, a Lewis acid, such as magnesium ion, is known to accelerate the electron-transfer rate. In this study, we investigated the effect of Lewis acids on the radical-scavenging activities of hydroquinone and its methylated derivatives as well as on their oxidation potentials to clarify the radical-scavenging mechanisms of hydroquinones.日本化学会第95春季年会